I believe you are the one who have try Linux on Live-CD version. Especially a cool projects like Knoppix, Ubuntu.
Now FreeBSD have a live-CD version, they call FreeSBIE or A FreeBSD live CD.
The FreeSBIE current version is 1.1 is based on FreeBSD 5.3, FreeSBIE support several of desktop environment, and you should use shell only.
You can download FreeSBIE-1.1.iso (610MB) from FTP or Bit Torrent. Now FreeSBIE support only i386 and AMD64.